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Thread: Documented results from replacing the 12 FV factory stock with an Oryx Chassis

  1. #26
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    Those are base to tip O.A.L. measurements. The TMKs have pretty long tips. The SMKs are not as long and the tips aren't as far into the rifling. I have measured the chamber and set the seating depth accordingly.
    When I reload, I actually measure all my loads from cartridge base to ogive so I can be sure I am creating a consistent jump.
    I publish the data with the base to tip (O.A.L.) measurement to allow readers to compare with the SAAMI recommended O.A.L.

  2. #27
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    Thanks. Yep, mine are tip to base, 77gn SMK's. If I set them to 2.300 I am touching the lands. I wonder if Savage started cutting .223 throats a little longer.

    I know it is not a whole lot of difference, as long as the jump to lands is consistent.

  3. #28
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    My 12 FV .223 has almost the same chamber depth as one of my range buddy's 12 FV .223.
    My loads for the 77 SMKs are at 2.298 to 2.309 and the 2.309 is about 0.009 off the lands and is the deepest I have seated the bullets out.
    The 77 TMKs have a longer tip, so the O.A.L.s are longer
    but the cartridge base to ogive is almost the same as for the 77 SMKs.
    O.A.L.s of 2.339 to 2.340 are around the 0.020 jump with the 77 TMKs and I have loaded out to a longs as 2.353 just to see if getting closer to the lands improves accuracy. It didn't. The best loads, under 0.250, are all between 2.339 and 2.343 O.A.L. The next best loads, groups around 0.260, are about 0.005 closer or further from the lands.

    Our chambers really aren't that much different.
    It is very possible that you have a slightly shorter chamber.
    When a chamber cutting reamer wears, they would have to reset their cutting depth for the new reamer. It is possible that the reamer for your barrel was a bit shorter and they didn't adjust it enough.
    Actually, your chamber is closer to SAAMI specs than ours.

    I have about 1,600 rounds down my 12 FV .223 barrel, but I don't see the same rate of wear on the .223 chamber that I have seen with the 6.5mm Creedmoor after about the same number of rounds (0.036 deeper than when it was new).

  4. #29
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    Yeah, they are close enough to not be unusual. I could blame it on my having an Axis instead of a 110 series, but, I understand that all the barrels are treated the same, regardless of final model they are installed on. Regardless, as long as mine shoots as well as it does the shorter throat doesn't bother me.

  5. #30
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    I wouldn't be worried, I would consider it an extra value because it will add life to your barrel by giving you more steel to erode.

    My first Savage .308 had a chamber that was 0.080 longer than SAAMI from the factory. I shot 6500 rounds and the chamber eroded by another 0.090 making me seat the bullets out longer and longer to maintain the jump. After 6,500 rounds I was seating the rounds out at 2.970 compared to the SAAMI 2.800 recommended O.A.L.
    At that O.A.L. I couldn't maintain consistent neck tension and had to rebarrel. I figure that deep chamber cost me about 5000 rounds of use.
    I consider consider a short chamber a gift instead of a problem.

  6. #31
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    Thanks. Right now I kinda feel the same way since this barrel shoots so well.

  7. #32
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    I tried another experiment with the Savage 12 FV .223 with the Oryx chassis using the 36X single power Sightron 1-inch tube scope with a target dot reticle. The action screws were torqued to 60 in.-lbs. prior to this session to match the Oryx chassis torque specs.

    I shot in two sessions on Thursday, Aug 16nd and Saturday August 22nd in Northern Virginia at 100 yards testing 69 gr TMK #7169 and 69 SMK #1380 bullets with IMR4166 powder and Remington 7 ½ BR primers. Somewhat uniquely, the 69 grain bullets with IMR4116 powder allow a range of loads that include both the 10th and 12th reflection exit times without exceeding Pmax. The 60 and 69 grain bullets are about the only bullet weights that can manage that. The test was to try one load of each at the 10th reflection exit time (1.134 msec. around 2584 to 2590 fps) and one load of each at the 12th reflection exit time (1.361 msec. at 2954 to 2589 fps) and them compare the results. Those exit times should be the sweet spots for a 26-inch 3% carbon steel barrel with a 0.040-inch recessed crown. (Estimated pressure and exit times were obtained from QuickLOAD.)

    Temperatures on Friday and Saturday morning were both 75 to 85 degrees with standard high humidity from 8 to 10:30 AM with winds from 3 to 5 mph. Altitude of the range is 250 feet above sea level.
    Although the bullets were of two types, the loads at each end of the range were quite similar with only slight variations in seating depth and trim length to accommodate the bullet themselves and their specific seating depths to achieve a 0.020 jump.
    Even though the muzzle velocity of the 10th reflection averaged 374 fps higher than the 12th reflection and the pressure averaged 19,588 psi higher, there were no difference in pressure signs on the primers and no difference in the feel of the bolt on extraction.

    The load description field shows the powder and charge, the O.A.L., the trim length, and the bullet exit time from the 26-inch barrel.

    # Grps Load Description Bullet Weight Velocity Average Median St Dev 1 2 3 4
    4 IMR4166 21.3 gr 2.348 1.747 wf 1.361 * 75/76 deg. F. Rem 7 ½ Oryx 60 in.-lbs. 37361 psi Sierra TMK #7169 69 2581 0..266 0..266 0.038 0.219 0.264 0.267 0.313
    4 IMR4166 24.4 gr 2.344 1.744 wf 1.134 * 79/78 deg. F. Rem 7 ½ Oryx 60 in-lbs. 57246 psi Sierra TMK #7169 69 2954 0.323 0.333 0.093 0.211 0.285 0.381 0.416
    4 IMR4166 21.7 gr 2.336 1.742 wf 1.361 * 83/82 deg. F. Rem 7 ½ Oryx 60 in.-lbs. 37456 psi Sierra SMK #1380 69 2594 0.276 0.290 0.041 0.215 0.288 0.292 0.308
    4 IMR4166 21.0 gr 2.304 1.739 wf 1.134 * 83/77 deg, F. Rem 7 ½ Oryx 60 in.-lbs. 56747 psi Sierra SMK #1380 69 2569 0.277 0.281 0.035 0.233 0.266 0.295 0.313
    16 0.285 0.287 0.056




    The second load of TMKs were really impacted by the last groups of .416. Up until that group, the first three groups were averaging a somewhat respectable 0.292. The POI for the 10th reflection loads was 4 ½ inches higher than the 12th reflection loads. I expected some change in the POI but I was really surprised it was that much for a 375-fps change in muzzle velocity. That may have broken my concentration a bit, but I don’t think it caused the two larger groups testing that particular load although it was the first 10th reflection load tested.
    That again shows how shooter induced variations can ruin good data. I have no explanation for that result, other than an error by the nut behind the trigger.
    Comparing the results by 10th and 12th reflection time:
    I gathered the data for each reflection time so I could compare the results by reflection time.
    With the 0.416 group:
    Refl. Exit Time Average Median St Dev
    10th 1.134 0.300 0.290 0.070
    12th 1.361 0.271 0.278 0.037
    Delta 0.029 0.013 0.032

    Excluding the 0.416 group:
    Refl. Exit Time Average Median St Dev
    10th 1.134 0.283 0.285 0.056
    12th 1.361 0.271 0.278 0.037
    Delta 0.013 0.008 0.018
    The results, with and without the single 0.416 group that bothered me so much, really didn’t show a marked difference in results for the different reflections, given that the number of groups for each reflection was only 8 (with the 0.416 group) and 7 and 8 (without the 0.416 group). The differences between the combined data for the two reflections (even when including the 0.416 group) is within the normal variation in data for almost identical loads with the same velocity and pressure the I have been reporting.

  8. #33
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    Interesting results.

    Have you ever overlayed (or plotted) shot groups to see what a 20round (or more) shot group would look like? I find that extremely interesting sometimes. If everything is going well and shooting is consistent the overall group size does not change much, but, it will start to show that nice bell curve distribution.

  9. #34
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    "POI for the 10th reflection loads was 4 ½ inches higher than the 12th reflection loads"- this is very surprising and I would not have expected such a change as well.

  10. #35
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    charlie b, I have shot 25-round groups into a 0.6 inches ragged hole, multiple times, even though barrel heating dropped the POI between 1/4 to 1/2 an inch toward the end of about 7 to 8 shots. I wait for the barrel to cool a couple of times and finish the group. I even aimed slightly to the right and left so I could identify the individual groups of 8 so I could measure them too.

    DesertDug, I didn't think 375 fps would have made that much difference in POI.
    The first group was a 12th reflection group and it was dead on the POA.
    I figured the POI would be higher for the 10th reflection so I chose a 0.7 inch diamond at the bottom of a 8 1/2 by 11 inch target I print myself.
    Fortunately, there was enough room for the group to hit at a higher diamond, so I just kept the POA at the bottom and let the groups print at the top.
    When I went back to shooting the 12th reflection, the next load was right at the POA, so it wasn't a scope issue.
    Then I shot the next 10th reflection and the POI was right back to being high.
    I guess I have to get out my ballistic calculator and see what was happening.

  11. #36
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    I understand about the group size. If you took that 20 round group and broke it up into 5round groups you'd probably still have a few in the 0.3" range or less.

    I would expect the POI to change a bit but the 4" does surprise me too. My ballistics table says there is less than 1" difference in drop at 100yd for a 400fps change in vel. Curious.

  12. #37
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    I just took the data from QuickLOAD and entered it into QuickLOAD Target.
    The 69 TMKs should have been 1.27 inches higher.
    The 69 SMKs should have been 0.78 inches higher.

    I still can't explain it but I know where I aimed and where the bullets impacted.
    The 12th reflection POA was at the middle row diamond crosshair aim point and hit just about right at the middle row crosshairs for both the 69 TMKs and the 69 SMKs.
    The 10th reflection POA was at the bottom row diamond crosshairs (2 5/16 lower) but hit almost at the upper row diamond crosshair aim point.
    Actual measurements from the target show:
    The 10th reflection for the 69 TMK's POI was 4.25 inches higher than the 12 Reflection POA at the bottom row diamond crosshair.
    The 10th reflection for the 69 SMK's POI was 4.75 inches higher than the 12th reflection POA at the bottom row diamond crosshair.
    The relative positions for the TMKs and SMKs is the opposite of what the ballistic calculator in QuickTarget predicted.

  13. #38
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    I believe you. I've had curious POI changes in the past as well and I never figured it out. I just figured it was in my shooting, much like pistols where higher velocity bullets hit lower than low vel bullets due to the time in the barrel and recoil.

    Yours is different since you have clearly shot loads with this kind of vel difference before without a huge change in POI.

  14. #39
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    Again not a scientist but I am still weirded out with my real DOPE. They shoot way hotter than they could possibly be. Or the trajectory is flatter..


    Sent from my iPhone using Tapatalk

  15. #40
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    Here are more results with the Savage 12 FV .223 with the Oryx chassis using the 36X single power Sightron 1-inch tube scope with a target dot reticle. The action screws were torqued to 60 in.-lbs. prior to this session to match the Oryx chassis torque specs.

    This session, held in Northern Virginia at 100 yards on Tuesday, Aug 27th at temperatures from 67 to 69 degrees from 8 AM to 10:30 AMM with winds from 3 to 5 mph with some misting rain at times. Altitude of the range is 250 feet above sea level.

    All the loads were shot using Lapua brass using Remington 7 ½ small rifle primers. All bullets were loaded to achieve a 1.361 msec. exit time (12th reflection) to stay well under Pmax using the 77 grain bullets with IMR4166 powder. The 1.361 exit time should be the sweet spot for a 26-inch 3% carbon steel barrel with a 0.040-inch recessed crown.

    For this session, I loaded IMR4166 Enduron powder and 77 grain Tipped Match King #7177 bullets with the seating depths for the 77 grain bullets to achieve the a jump to the rifling – 0.030 to 0.020 – and then adjusted the seating depth by less than 0.005 thousandths to achieve the 1.361 exit time to accommodate variations in the brass trim length. As a result, all the loads are quite similar with only slight variations in seating depth and trim length.

    The load description field shows the powder and charge, the O.A.L., the trim length, and the bullet exit time from the 26-inch barrel.

    # Grps Load Description Bullet Weight Velocity Average Median St Dev 1 2 3 4
    5 IMR4166 21.0 gr 2.340 1.746 wf 1.361 * 67/66 deg. F. Rem 7 ½ Oryx 60 in.-lbs. Sierra TMK #7177 77 2539 0.207 0..174 0.055 0.161 0.167 0.174 0.250
    4 IMR4166 21.0 gr 2.338 1.744 wf 1.361 * 69/68 deg. F. Rem 7 ½ Oryx 60 in-lbs. Sierra TMK #7177 77 2539 0.238 0.236 0.068 0.163 0.202 0.269 0.316
    4 IMR4166 21.0 gr 2.336 1.742 wf 1.361 * 71/69 deg. F. Rem 7 ½ Oryx 60 in.-lbs. Sierra TMK #7177 77 2539 0.310 0.279 0.129 0.193 0.247 0.310 0.489
    4 IMR4166 21.0 gr 2.333 1.739 wf 1.361 * 73/69 deg, F. Rem 7 ½ Oryx 60 in.-lbs. Sierra TMK #7177 77 2539 0.332 0.331 0.033 0.299 0.300 0.353 0.366
    17 0.268 0.264 0.049
    .










    For this session, the 12 FV averaged 0.268 for 17 groups. I shot a 5th group on the first load at 0.282 that somehow won’t show in the table above. That group is included in the 0.207 load average.

    As you can see, there was a marked difference in performance after the second load. The range officer on duty asked me to help a new shooter with a new rifle on an adjacent lane to get his new scope on paper. After finding that his scope mounts were loose and torqueing them, I helped him get on paper and adjust his scope. I never quite got back to the same level of concentration after that. The last load was rushed trying to make up time lost so I could finish on my schedule. I think you can see what happens to my accuracy when I rush. The last group on the third load had one flyer and the entire 4th load was mediocre across the board.

    It’s too bad I couldn’t maintain the concentration that I have for the first load. I was really in the groove for the first 8 groups then things started to go downhill.

    Including this session, the TMK and SMK session summaries are shown below:

    Date ---- Avg. --- # Grps - SMK Avg. - # Grps.
    July 19 - 0.278 --- 16 ------ .240 ------ 4
    July 26 – 0.280 –- 16
    Aug 2 – 0.264 ---- 16
    Aug 12 – 0.280 -- 16
    Aug 17 – 0.279 --- 8 ------- 0.298 ----- 8
    Aug 22 – 0.295 --- 8 ------- 0.276 ----- 8
    Aug 27 – 0.268 -- 17
    Avg. ---- 0.275 – 108 ------ 0.278 ---- 20

    TMK Median was 0.273 & the SMK Median was 0.272.
    Min TMK load averaged 0.263 (-0.013) - Min SMK load averaged 0.240 (-0.038)
    Max TMK load averaged 0.295 (+0.019) - Min SMK load averaged 0.298 (+0.020

    The two 77 grain Sierra Match King and Tipped Match King bullets are performing pretty much the same and I suspect that the variations are more due to shooter induced variations than bullet performance.

    All the groups of the 77 gr TMKs and 77 Gr SMKs were shot with IMR4166 powder and those two powder-bullet combinations ranked 1 & 2 respectively out of all the powder bullet combinations shot with this rifle. I still think that it is incredible that two 77 gr bullets have the best averages when they aren’t even supposed to stabilize in the 1:9 twist barrel on this rifle.

  16. #41
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    Here are the results of another session with the 12 FV .223 that took place in Northern Virginia on Monday morning, September 9th at 100 yards. Temperatures on Monday were from 73 to 82 degrees with winds from 4 to 7 mph. Altitude of the range is 250 feet above sea level. For this session, the 12 FV was mounted in the Oryx chassis using the 36X single power Sightron 1-inch tube scope with a target dot reticle. The action screws were torqued to 60 in.-lbs. prior to this session to meet the Oryx chassis torque specs.

    All the loads were shot using Lapua brass with Remington 7 ½ small rifle primers. All bullets were loaded to achieve a 1.361 msec. exit time (12th reflection) to stay well under Pmax using the 77 grain bullets with IMR4166 powder. Loading for the 10th reflection at 1.134 msec. would have been well above Pmax pressures and wasn’t attempted. The 1.361 exit time should be the sweet spot for the 12th reflection for a 26-inch 3% carbon steel barrel with a 0.040-inch recessed crown.

    Sorry for the primitive format for the following entries but the new server doesn’t seem to allow the formatting that I was able to do with the previous server.
    All loads were shot with IMR4166 powder, Sierra 77 gr TMK #7177 bullets with an Oryx chassis torqued to 60 in.-lbs. and at 1.361 msec. exit time.

    # Grps. – O.A.L. – Trim --- Vel. ---- Avg. -- Median - St. Dev. ----- 1 ------ 2 ------- 3 ------- 4
    --- 4---- 2.358 --- 1.746 – 2543 --- 0.285 -- 0.286 --- 0.042 --- 0.245 – 0.252 – 0.320 -- 0.322
    --- 4 --- 2.355 --- 1.743 – 2543 --- 0.286 – 0.292 --- 0.022 --- 0.257 – 0.282 – 0.302 – 0.303
    --- 4 --- 2.355 --- 1.741 – 2543 --- 0.244 – 0.238 --- 0.067 --- 0.181 – 0.195 – 0.281 – 0.320
    --- 4 --- 2.350 --- 1.738 – 2543 --- 0.287 -- 0.281 --- 0.074 --- 0.206 – 0.263 – 0.298 – 0.382
    -- 16 ------------------------------------ 0.276 – 0.282 --- 0.053

    Today’s results reduced the overall average 5 round group size of all loads shot so far to 0.303 for 270 groups.
    Previous results with Sierra 77 gr TMK #7177 bullets with IMR4166 powder and Rem 7 ½ primers averaged 0.278 for 134 groups.
    Today’s results with the same bullet, powder and primer averaged 0.276 for 16 groups which is just about on the overall average.

    Today’s one good load average of 0.244 was the 7th best load of all the 12 V .223 loads, proving that even a blind pig can find an acorn once in a while.

    After today’s session, the 77 gr TMKs current overall average remains at 0.278 for 150 groups.

    The 77 gr TMK #7177 bullets continue to amaze with their accuracy out of the 1:9 twist barrel on the 12 FV when they are supposed to be marginally stable. Between the 77 gr TMKs and their cousins the 77gr SMKs, they hold the first two ranks of all the bullets shot in the 12 FV .223.
    When all the groups shot including the lighter bullets are included, the overall factory stock 88 groups average 0.356.

    The Oryx chassis 180 groups average 0.278, but the Oryx stock was used to exclusively shoot the heavier 69 and 77 grain bullets which have shot much more accurately than most of the lighter bullets so that has skewed the comparison of the stock and chassis.

    That computes to an improvement of 21.9% for the Oryx stock, but I think that is not truly representative of the difference in the performance of two stocks. I tend to shoot the bullets that shoot the most accurately, so I have been concentrating on the 69 and 77 grain bullets over the most recent sessions and the better bullets, mostly shot on the Oryx stock have biased the results. For that reason, I did a comparison of the factory stock and Oryx chassis should be based on similar bullets and similar primers.

    ------------- Factory Stock ------------------- Oryx Chassis -------------
    Bullet --------- Avg. ---# Grps. ------ Avg. --- # Grps. % Improvement
    69 SMK ------- 0.329 ----- 10 --------- 0.300 --- 15 ------- 8.7 %
    69 TMK ------- 0.290 ----- 21 --------- 0.258 --- 07 ------- 11.1 %
    77 SMK ------- 0.344 ----- 11 --------- 0.268 --- 19 ------- 22.1 %
    77 TMK ------- 0.272 ----- 20 --------- 0.279 --- 130 ----- (-2.4%)
    All 69 & 77s - 0.286 ----- 62 --------- 0.279 --- 180 ------ 2.3%

    Even this comparison is slightly biased by using different jumps on some of the early data but the sample sizes are so small that further splitting out the data introduces the influence of ‘shooter induced variations’ that invalidates any conclusions. Interestingly, the average of the 77 gr TMK #7177 bullets with the Oryx stock is the only bullet that has better numbers with the factory stock.

    It turns out that the 77 gr TMK groups shot with the factory stock were all shot with CCI BR- 4 primers while the 77 gr TMKs shot with the Oryx chassis had 121 groups shot with Remington 7 ½ BR primers (0.280 average) and only 21 groups shot with CCI BR-4 primers (271 average). When the primer to primer results are compared, the results are just about dead even for the 77 gr TMKs.
    Because there are so many more groups (130) shot with the 77 gr TMKs compared to all the others, the combined 69 and 77 grain SMKs and 69 gr TMKs results between the factory stock and the Oryx chassis are just about even.
    The factory stock 62 total groups average 0.286 and the 180 Oryx chassis groups average 0.279 resulting in only a 2.3% overall improvement.

  17. #42
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    Thanks again for this kind of work. The attention to detail is great for scientific analysis.

    And, yes, even this blind pig gets a great group every now and then too :)

    Sent from my SM-P580 using Tapatalk

  18. #43
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    Here are more results with the Savage 12 FV .223 with the Oryx chassis using the 36X single power Sightron 1-inch tube scope with a target dot reticle. The action screws were torqued to 60 in.-lbs. prior to this session to match the Oryx chassis torque specs.

    This session, held in Northern Virginia at 100 yards on Wednesday, Sept 25th at temperatures from 57 to 53 degrees from 8 AM to 11:00 AM with winds from 1 to 3 mph. Altitude of the range is 250 feet above sea level.

    For this session, I was experimenting with the relative accuracy for two Sierra 69 grain match bullets at two different velocities – each were chosen to match the exit time for a different reflection time for the shock wave that proceeds down the barrel at 19,107 fps for this particular barrel length and steel type.
    Each bullet type was loaded to achieve both a 1.134 msec. exit time (10th reflection) relatively close to Pmax and a 1.361 msec. exit time (12th reflection) to stay well under Pmax.
    Both the exit times at the two different reflections should be on a sweet spot for a 26-inch 3% carbon steel barrel with a 0.040-inch recessed crown.

    I loaded IMR4166 Enduron powder and 69 grain Sierra SMK #1380 and Sierra 69 gr Tipped Match King #7169 bullets with the seating depths for the 77 grain bullets to achieve the a jump to the rifling – 0.030 to 0.020 – and then adjusted the seating depth by less than 0.005 thousandths to achieve the desired exit times to accommodate variations in the brass trim length. All the loads were shot using Lapua brass using CCI BR-4 small rifle primers.

    As a result, all the loads are quite similar with only slight variations in seating depth and trim length.

    The load description field shows the powder and charge, the O.A.L., the trim length, and the bullet exit time from the 26-inch barrel.
    # Grps Load Description Bullet Weight Velocity Average Median St Dev 1 2 3 4
    4 IMR4166 21.7 gr 2.345 1.752 wf 1.361 * 59/59 deg. F. CCI BR-4 Oryx 60 in.-lbs. Sierra SMK #1380 69 2594 0.253 0.259 0.036 0.211 0.243 0.257 0.302
    4 IMR4166 21.3 gr 2.353 1.752 wf 1.361 * 64/64 deg. F. CCI BR-4 Oryx 60 in-lbs. Sierra TMK #7169 69 2586 0.285 0.277 0.027 0.263 0.266 0.287 0.322
    4 IMR4166 24.9 gr 2.347 1.751 wf 1.134 * 70/69 deg. F. CCI BR-4 Oryx 60 in.-lbs. Sierra SMK #1380 69 2970 0.264 0.260 0.048 0.218 0.227 0.293 0.316
    4 IMR4166 21.0 gr 2.350 1.750 wf 1.134 * 73/73 deg, F. CCI BR-4 Oryx 60 in.-lbs. Sierra TMK #7169 69 2954 0.317 0.323 0.053 0.258 0.286 0.360 0.364
    16 0.280 0.276 0.046
    .



    The SMKs averaged 0.258 and the TMKs averaged 0.301.
    However, the 10th reflection exit times averaged 0.290 and the 12th reflection exit times averaged 0.269.

    But those averages were both skewed by the last TMK 10th reflection load that averaged 0.317 (no explanation other than shooter induced variation).

    In fact, the best load was a 12th reflection SMK load at 0.253 and the 2nd best was a 10th reflection SMK load at 0.264.
    The 12th reflection TMK load average 0.264.

    I think I have better retest this in opposite order to see if the early loads get the benefit of better concentration from a 76-year-old shooter.

  19. #44
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    This session, held in Northern Virginia at 100 yards on Saturday, Sept 28th at temperatures from 69 to 73 degrees from 8 AM to 10:30 AM with winds from 3 to 6 mph. This experiment was performed using the Savage 12 FV .223 with the replacement Oryx chassis using the 36X42 single power Sightron 1-inch tube scope with a target dot reticle. The action screws were torqued to 60 in.-lbs. prior to this session to match the Oryx chassis torque specs.

    Altitude of the range is 250 feet above sea level. The morning was overcast as can be seen by the relatively consistent temperatures during the morning – the cloud cover kept the temperatures from dropping too severely overnight and reduced the heating by the sun after sun-up. But the light winds were blowing from directly behind the firing line from 9 AM onward and did cause some swirling within the berms protecting the range so it was very difficult to read the wind.

    After experiencing some fairly severe accuracy drop off when shooting the last load during recent sessions, I decided to extend the test I performed during the last session using two Sierra 69 grain match bullets at two different velocities – each were chosen to match the exit time for a different reflection time for the shock wave that proceeds down the barrel at 19,107 fps for this particular barrel length and steel type. For this session, I reversed the testing sequence of the loads, shooting the faster loads first. I was trying to see if I could eliminate the poor results I was experiencing with the last load at the last two sessions.

    Each bullet type was loaded to achieve both a 1.134 msec. exit time (10th reflection) relatively close to Pmax and a 1.361 msec. exit time (12th reflection) to stay well under Pmax. Both the exit times at the two different reflections should be on a sweet spot for a 26-inch 3% carbon steel barrel with a 0.040-inch recessed crown.

    I loaded IMR4166 Enduron powder and 69 grain Sierra SMK #1380 and Sierra 69 gr Tipped Match King #7169 bullets with the seating depths for the 77 grain bullets to achieve the a jump to the rifling – around 0.020 – and then adjusted the seating depth by less than 0.005 thousandths to achieve the desired exit times to accommodate variations in the brass trim length. All the loads were shot using Lapua brass using CCI BR-4 small rifle primers.
    As can be seen in the following table, all the loads are quite similar with only slight variations in seating depth and trim length.

    The load description field shows the powder and charge, the O.A.L., the trim length, and the bullet exit time from the 26-inch barrel.
    # Grps. Load Description Bullet Weight Velocity Average Median St Dev 1 2 3 4
    4 IMR4166 24.4 gr 2.355 1.754 wf 1.134 * 69/69 deg. F. Oryx 60 in.-lbs. Sierra TMK #7169 69 2953 0.308 0.308 0.024 0.279 0.302 0.314 0.336
    the4 IMR4166 24.9 gr 2.349 1.753 wf 1.134 * 71/71 deg. F. Oryx 60 in-lbs. Sierra SMK #1380 69 2970 0.259 0.265 0.012 0.241 0.264 0.265 0.266
    4 IMR4166 21.3 gr 2.353 1.752 wf 1.361 * 74/72 deg. F. Oryx 60 in.-lbs. Sierra TMK #7169 69 2581 0.315 0.323 0.076 0.216 0.316 0.329 0.400
    4 IMR4166 21.7 gr 2.346 1.751 wf 1.361 * 79/73 deg, F. Oryx 60 in.-lbs. Sierra SMK #1380 69 2593 0.305 0.276 0.080 0.245 0.269 0.283 0.422
    16 0.297 0.281 0.056






    The resulting average group sizes were not quite as good as at the last session but the fall off in accuracy with the last load didn’t occur.
    At this session, I shot only the one remaining load from the 6.5mm Creedmoor rifle so I had more time to attend to this experiment and didn’t have to rush to finish before a ceasefire was going to be called. At the previous session I was swapping rifles to allow one to cool while I shot the other. It may have created loss of concentration toward the end of the session. The lower work load probably had something to do with the more consistent results, even if the overall average for the session was higher than for the last session.
    Even then, only one load produced a sub 0.3 group average at today’s session. I guess that shows that a shooter (at least this shooter) doesn’t perform consistently from session to session, although the results are still pretty impressive, especially for a low-cost mass-produced rifle (even if it has a replacement stock). The natural variations in shooting performance from session to session is another reason to gather relatively large samples when making comparisons and attempting to form any conclusions.

    Combining the results for the last two sessions, the averages for the bullet – reflection sorted by reflection for the last two sessions are:
    Sierra 69 grain SMK # 1380 – 1.134 msec. exit time – 10th reflection (24.9 gr IMR4166 – 2970 fps) for 8 groups = 0.261
    Sierra 69 grain SMK #1380 – 1.361 msec. exit time – 12th reflection (21.7 gr IMR4166 – 2593 & 2594 fps) for 8 groups = 0.279
    Sierra 69 grain TMK #7169 – 1.134 msec. exit time – 10th reflection (24.4 gr IMR4166 – 2984 fps) for 8 groups = 0.312
    Sierra 69 grain TMK #7169 – 1.361 msec. exit time – 12th reflection (21.3 gr IMR4166 – 2581 & 2584 fps) for 8 groups = 0.300
    For the 69 grain bullets, the SMKs seem to be performing better.

    Comparing By Bullet for the last two sessions:
    69 grain SMK # 1380 bullets for 16 groups = 0.270
    69 grain TMK # 7169 bullets for 16 groups = 0.306

    Comparing By Reflection for the last two sessions:
    10th reflection (both bullets) for 16 groups = 0.287
    12th reflection (both bullets) for 16 groups = 0.289
    There doesn’t appear to be any appreciable difference based upon reflection.

    Overall results to date for the two 69 grain bullet types with IMR 4166 powder regardless of seating depth, trim length or velocity are as follows:
    Sierra 69 grain SMK # 1380 = 0.289 for 49 groups
    Sierra 69 grain TMK # 7169 bullets = 0.295 for 53 groups
    Again, the SMKs show a slight edge in accuracy across a pretty large sample set.

    However, the 77 grain Sierra bullets are performing almost the opposite with respect to accuracy.
    Sierra 77 grain SMK #9377 = 0.296 for 31 groups.
    Sierra 77 grain TMK #7177 = 0.278 for 150 groups.

  20. #45
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    I haven't been keeping up this thread because I thought that there was enough .223 data here to provide results that most reloaders could use to test loads with their rifles and I had justified the switch to the Oryx chassis as far as I was concerned.

    As some of you already know, I sort of dropped off this forum when my wife died and it took me a while to get back into shooting again. The first rifle I tried was this 12 FV .223 with the Oryx stock. Thank you all for your condolences and good wishes. It means a lot to me.


    The first day at the range was a real wake-up call.
    Click image for larger version. 

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    But I knew that I had to get out and do things that would occupy my mind.
    From that session, I realized what being away from shooting for over a month did to my accuracy.

    I went back to the range in January and then again in February and I started to get back to my normal set up and had a good day in February.
    Click image for larger version. 

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    After commenting a few times on other threads, I figured that some of you might get some benefit from seeing what not shooting regularly might be doing to your own accuracy.
    I realize that not every one has the luxury of shooting as much as I was shooting but apparently it really helps consistency.

    I tried a bit different format with this most recent data because it is easier to get the columns in line.
    Hopefully, you all find this data easier to read.

  21. #46
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    Yes, not shooting on a regular basis screws me up as well. Also, shooting different rifles in the same session can put me off a bit. Especially going from the varmint trigger to std accutrigger. When I take two rifles to the range I try to shoot the one with the worst trigger first. :)

  22. #47
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    I like the new data-in-pic format. Makes reading on my phone easier, for sure.

  23. #48
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    Thanks for the feedback.
    I hadn't thought of how difficult it would be to read lots of text on a small screen.
    I'll adjust to using the new format from now on.

  24. #49
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    This will be the last entry for a while. They just closed our rifle/pistol range, the skeet and trap ranges, our indoor and outdoor archery ranges, and the indoor air pistol/air rifle range because of the corona virus.
    Even though the rifle/pistol range is an outdoor range with plenty of space to maintain separation, a majority of RSOs, who are mostly geezers like me, didn't want to be exposed. I can understand that, especially given the panic about the virus in Northern Virginia and in Washington DC.

    The following data is from my last range visit on the 16th, the day before they closed the ranges.

    Here is my most recent data.
    Winds in the early morning were from 3 to 5 mph with temperatures rising pretty rapidly from 33 to 46 from 8 AM to 11 AM. The temps had risen to 36 degrees before I actually put the first round down range because I spent some time BSing with the RSO - a good friend.
    I shot VV N140 powder, a temperature sensitive powder that I had loaded from 33 to 46 degrees based on my prediction of the temperatures over the time I intended to shoot. Even with the later than planned start, my predicted temperature was never off by more than 3 degrees from what I loaded for.

    Click image for larger version. 

Name:	12 FV .223 Oryx Mar 16 2020.JPG 
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  25. #50
    Basic Member hamiltonkiler's Avatar
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    Quote Originally Posted by CFJunkie View Post
    This will be the last entry for a while. They just closed our rifle/pistol range, the skeet and trap ranges, our indoor and outdoor archery ranges, and the indoor air pistol/air rifle range because of the corona virus.
    Even though the rifle/pistol range is an outdoor range with plenty of space to maintain separation, a majority of RSOs, who are mostly geezers like me, didn't want to be exposed. I can understand that, especially given the panic about the virus in Northern Virginia and in Washington DC.

    The following data is from my last range visit on the 16th, the day before they closed the ranges.

    Here is my most recent data.
    Winds in the early morning were from 3 to 5 mph with temperatures rising pretty rapidly from 33 to 46 from 8 AM to 11 AM. The temps had risen to 36 degrees before I actually put the first round down range because I spent some time BSing with the RSO - a good friend.
    I shot VV N140 powder, a temperature sensitive powder that I had loaded from 33 to 46 degrees based on my prediction of the temperatures over the time I intended to shoot. Even with the later than planned start, my predicted temperature was never off by more than 3 degrees from what I loaded for.

    Click image for larger version. 

Name:	12 FV .223 Oryx Mar 16 2020.JPG 
Views:	21 
Size:	52.8 KB 
ID:	7005
    I’m I reading that the smk grouped better than the tmk?
    Dang.


    Sent from my iPhone using Tapatalk

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